From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: John Stultz <john.stultz@linaro.org>
Cc: Thomas Richter <tmricht@linux.ibm.com>,
Kees Cook <keescook@chromium.org>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: REGRESSION?: debugfs: inode: debugfs_create_dir uses mode permission from parent
Date: Wed, 13 Jun 2018 06:58:53 +0200 [thread overview]
Message-ID: <20180613045853.GB1246@kroah.com> (raw)
In-Reply-To: <CALAqxLVCpyKzGJPVtBuipnZbGbDC_Z0rPBrn-J2mkMsQsSvdtA@mail.gmail.com>
On Tue, Jun 12, 2018 at 03:40:41PM -0700, John Stultz wrote:
> Hey all,
> I noticed recently that linus/master (plus patches) stopped booting
> to UI on HiKey960, and I bisected the issue down to:
> 92170b62f1c1 ("debugfs: inode: debugfs_create_dir uses mode permission
> from parent")
>
> On the HiKey960 board, we mount debugfs via:
> mount debugfs /sys/kernel/debug /sys/kernel/debug mode=755
>
> But since the change, it seems most of the nodes in /sys/kernel/debug
> are: drwx------
>
> Which ends up breaking the egl library, keeping it from loading.
While the debugfs change is now reverted in Linus's tree, I find it
"odd" that a debugfs change would cause egl from loading entirely. No
userspace code should depend on debugfs files being there or not. If it
does, that's a bug as debugfs is for _debugging_ stuff, it should not be
an interface between user/kernel that userspace requires for basic
functionality like booting.
And yes, I know all about the crazy qualcom batter api, where they
shoved it into debugfs and ignored the built-in kernel api, that should
be fixed now. If this is a new one-of-those types of problem, I need to
know so it can get resolved.
thanks,
greg k-h
prev parent reply other threads:[~2018-06-13 4:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-12 22:40 REGRESSION?: debugfs: inode: debugfs_create_dir uses mode permission from parent John Stultz
2018-06-12 22:52 ` Kees Cook
2018-06-12 22:53 ` John Stultz
2018-06-13 4:58 ` Greg Kroah-Hartman [this message]
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